1. Field of the Invention
The present invention relates to an optical component having a substantially cylindrical external shape, to a method for connecting the same, and to an optical module having the optical component.
2. Description of the Related Art
A capillary for an optical fiber is disclosed in Japanese Unexamined Patent Application Publication No. 11-160563 as an example of an optical component used for connecting an optical fiber to another optical fiber or optical device in the field of optical communications. An optical fiber is positioned so that the optical fiber optically connects with another optical fiber or optical device while the glass portion thereof is being inserted in the capillary. The capillary is generally cylindrical in shape, and is formed from ceramics or glass. A capillary formed from glass can be manufactured at low cost and with good precision of dimensions and symmetry by extending cylindrical glass tube to a small diameter. Such cylindrical optical component can be easily positioned with respect to all degrees of freedom other than the azimuthal angle about the cylinder axis, using the lateral surface of the cylinder as a reference.
While a cylindrical optical component such as the one described above is polished on the end face thereof or positioned with respect to another optical component or optical device, the lateral surface of the cylinder is gripped by a gripping member. Since the optical component and the gripping member come into contact with each other only at a point or a line parallel to the cylinder axis on the lateral surface of the cylinder, it is difficult to obtain a gripping force (frictional force) sufficient to position or fix the optical component. The optical component then comes out of position while polishing its end face, and polishing cannot be performed correctly, and the component becomes misaligned during connection to another optical component or optical device due to shrinkage of the adhesive when cured. When the force with which the optical component is gripped is increased in order to obtain adequate gripping force, the optical component may be damaged if it is composed of glass or another fragile material.
With an optical component whose end face is polished at an inclination angle with respect to the plane orthogonal to the cylinder axis, or an optical component such as one in which a plurality of optical fibers are inserted, its azimuthal angle about the cylinder axis must be aligned when the component is to be connected to another optical component or optical device. However, since the external peripheral shape of a cylindrical optical component is rotationally symmetrical with respect to the central axis of the cylinder, it is impossible to align the azimuthal angle about the cylinder axis using the external periphery as a reference.